If you've given your dog enough exercise? I just did a 2 hour hike off leash with my two. It was a little warm but very humid so felt hot. We stopped at the end of the hike and Mia actually laid down and looked pretty satisfied. I was pretty sure she'd come home and sleep. Nope. Neither of them did. Summer's been hopping up and down off the couch and then chewing on a bully stick. And Mia is being ridiculously hyper like I haven't seen her in a long time. Donuts around the house at full speed and barking at everything... I really don't see a correlation between exercise amount and how calm or hyper they are. The only time they're really pooped is after a full agility evening where they each get an hour of work and then are out at the field the rest of the evening.